The present invention relates to carpentry and brick layer's cutting tools and more particularly to a hand-operated circular saw having blade cutting depth adjustment device which is capable of leaning on a wall, a top of table and/or the ground to precisely cut a work object.
As we know that the conventional cutting machine is principally of the table type having a rotatable saw blade on the top for cutting lumbers, tiles and/or stones, on which the work piece are usually pushed to the saw blade. Because the work piece may be too large or too small to fit the saw blade, it is difficult to cut on the table type cutting machine. Thus a hand-operated circular saw appears in the market. This type of circular saw can be freely operated by the user because it is graspable by the hand of the user. However, its rapidly rotated saw blade may unintentionally hurt people or the user himself if he works unconsciously.
FIG. 1 shows a prior art hand-operated circular saw which comprises a graspable main body 10, a head 11, a threaded axis operated by a motor inside the head 11, a saw blade 13 wrapped onto the axis 12 and secured by a nut 14 and a guard 15 protected a great portion of the saw blade 13. This type of the hand-operated circular saw has a disadvantage that the guard 15 could not lean on object to cut a work piece.
FIGS. 2 and 3 show another prior art hand-operated circular saw 20 which comprises a graspable main body 21, a head 22, a threaded axis 23 operated by a motor inside the head 22, a guard 26 secured to the head 22 by a plurality of screws, an inner cover 261 wrapped on the guard 26 before a saw blade 24 secured onto the axis 23, an outer cover 262 wrapped to the outside of the inner cover 261 with an arcuate spring 28 disposed therebetween for providing the rotatable resilient force to the outer cover 262, an outer guard 27 disposed on the top of the guard 26 having a plurality of slots 271 in the peripheral wall for adjustably securing the outer guard 27 to the guard 26 by a plurality of bolts, an internally threaded block 272, a butterfly nuts 273 and a U-shaped handle 29 pivoted to the head 22 by screws 274. In operation, the outer guard 27 can be adjusted to lean on a wall in accordance with the cutting depth of a work piece and the covers 261 and 262 are immediately returned to their original positions right after the saw blade 24 removed from the work piece in order to prevent the dirt and the water from sprayed to the user. The adjustment of the outer guard 27 needs experience and must be tried again and again, and that's inconvenient.